Dipalladium complexes with bridging diorganosilyl ligands. Synthesis, structure, and properties of [LPd(μ-SiH(R)Ph)]2 (R = Ph or Me; L = PMe3, PEt3 or PMePh2)

Abstract

The complexes trans-PdEt₂L₂ (L = PMe₃, PEt₃ or PMePh₂) reacted with equimolar or twofold molar amounts of H₂SiPh₂ to produce various bimetallic palladium(II) complexes with bridging diphenylsilyl ligands, [(Me₃P)Pd(μ-SiHPh₂)]₂1, (Me₃P)Pd(μ-SiHPh₂)Pd(PMe₃)₂2 and [LPd(μ-SiHPh₂)]₂ (L = PEt₃3 or PMePh₂4), in moderate to good yields. Similar reactions using H₂SiMePh afforded the complexes [LPd(μ-SiHMePh)]₂ (L = PMe₃5 or PEt₃6). The isolated complexes were characterized by NMR spectroscopy and elemental analyses. Molecular structures of 3 and 5 have been determined by X-ray crystallography and suggest an agostic interaction between the μ-SiHPh₂ or μ-SiHMePh group and the Pd. The NMR study of the complexes revealed the bridging co-ordination of the silyl ligand with the Si–H–Pd three-center, two-electron bond in solution similar to that in the solid state. Complex 2 undergoes exchange of the PMe₃ ligands on the NMR timescale. The reactions of 2 with CO and HSPh afforded 1 and Pd(SPh)₂(PMe₃)₂, respectively.